There are many different pivot structures available for use. FIG. 1 illustrates a conventional pivot that has a generally N-shaped configuration formed from a rotary shaft 6, a stationary seat 7, and a fixing means 70. The rotary shaft 6 has a first end 61 in a form of round bar and a second end 62 in a form of flat bar having several mounting holes provided thereon for connecting the rotary shaft 6 to a rotary part of an article, such as a screen of a notebook computer. The stationary seat 7 is an L-shaped member having a short arm and a long arm. The rotary shaft 6 is rotatably connected to the stationary seat 7 by extending its round second end 62 through a hole on the short arm of the stationary seat 7 and putting a pivotal fixing means 8 around the second end 62. The fixing means 70 is fixedly connected to the long arm of the stationary seat 7 by extending an end into a hole formed on the long arm and then fixed at the other end to a stationary part of the article, such as a keyboard of the notebook computer. When the connection between the rotary shaft 6 and the stationary seat 7 of the pivot becomes loose, it may be adjusted to resume a suitable tightness by tightening the pivotal fixing means 8 against the short arm. A shortcoming of the pivot of FIG. 1 is its N-shaped body has a big volume and occupies too much space. When the pivot of FIG. 1 is used on a notebook computer, there would be a considerably big clearance between the rotary part (the screen) and the stationary part (the keyboard).
An in-line pivot having reduced volume and occupying less space as shown in FIG. 2 is therefore developed to replace the N-shaped pivot of FIG. 1. This in-line pivot includes a rotary shaft 4 and a stationary shaft 5. The rotary shaft 4 has a first end 41 in a form of hollow cylinder having two diametrically opposite cuts 411, and a second end 42 in a form of semi-circular solid bar. The stationary shaft 5 has a first end that can be axially and suitably tightly fitted in the first end 41 of the rotary shaft 4, such that the rotary shaft 4 may rotate relative to the stationary shaft 5, allowing a rotary part, such as the screen of a notebook computer, connected to the rotary shaft 4 to be swung and located at any desired inclined angle relative to a stationary part, such as the keyboard of the notebook computer. A second end 52 of the stationary shaft 5 is in a form of round solid bar. While this in-line pivot shown in FIG. 2 eliminates the drawbacks of the N-shaped pivot of FIG. 1, it has a disadvantage that the first ends 41 and 51 of the rotary and the stationary shafts 4 and 5, respectively, would become loosely connected to each other after the pivot has been used for a long time and the first ends 41, 51 are worn at their contact surfaces. The rotary part, such as the screen of a notebook computer, connected to the rotary shaft 4 would therefore automatically turn to cover the stationary part (i.e., the keyboard of the notebook computer) when a rotary angle is less than 90 degrees, or turn further to a straight angle relative to the stationary part when the rotary angle exceeds 90 degrees, instead of locating at a visual angle suitable for working.
Another disadvantage existing in both of the above two conventional pivots is when they are used on the notebook computer, the screen can not be conveniently turned relative to the keyboard within a limited angular range to provide an optimal visual angle even if the rotary shaft and the stationary shaft of the pivot are connected to each other in a suitably adjusted tightness.